<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    .d {
      display: flex;
    }
    .t {
      flex: 0 0 15%
    }
    .left,.right,.t {
      border: 1px solid #aaa;
    }
  </style>
</head>
<body>
  <div class="d">
    <button class="left">账户</button>
    <input type="text" class="t">
    <button class="right">元</button>
  </div>
</body>
</html>
